RECON: TNO occultation with 98WS31

Event between 98WS31 and star GA1180:01997628 with event index number of 1141961

Geocentric closest approach at 2021/10/25 16:14:27 UTC

J2000 position of star is 05:57:52.3 +29:57:54
Equinox of date position of star is 05:59:16.1 +29:57:56
Stellar brightness G=15.8, use SENSEUP=128 with the MallinCam and and exposure time of 2 seconds with the QHY174 camera.
Star is 5 degrees from the moon. Moon is 79% illuminated.
TNO apparent brightness V=23.6

TNO is 33.0 AU from the Sun and 32.5 AU from the Earth.
The TNO is moving 11.4 km/sec on the sky relative to the star, or, 1.7 arcsec/hr.
The 1-sigma error in the time of the event is 643 seconds.
The 1-sigma cross-track error in the shadow position is 3266 km.

The TNO has an absolute magnitude Hv=8.3
Diameter=134.3 km assuming a 5% albedo -- 11.8 sec chord
Diameter=54.8 km assuming a 30% albedo -- 4.8 sec chord
Dynamical classification is 3:2E
 
 
 
 
 
 
 
 

Star training set for 98WS31, (2021/10/25 16:14UT)
Object            RA         Dec     mag  sep  mel
Betelgeuse     05:56:21.2 +07:24:34  0.4 22.57  18
Alnath         05:27:40.4 +28:37:26  1.6  7.02   6
PPM 095117     05:57:57.0 +28:56:37  6.5  1.06   4
PPM 095186     06:00:19.8 +29:59:02  7.5  0.23   5
PPM 095148     05:59:14.5 +29:48:48 10.0  0.15   5
98WS31         05:59:16.2 +29:57:56 15.8         5
Positions are for equinox of date

Azimuth is measured in degrees eastward from north. North is at an azimuth of 0, due East is at an azimuth of 90 degrees, due South is 180, and due West is 270.

Do not use the listing below for the RECON CPC 1100 telescopes. This is provided for other non-team facilities.

Star training set for 98WS31, (2021/10/25 16:14UT)
Object            RA         Dec     mag  sep  mel
Betelgeuse     05:55:10.3 +07:24:26  0.4 22.57  18
Alnath         05:26:17.5 +28:36:23  1.6  7.02   6
PPM 095117     05:56:33.8 +28:56:32  6.5  1.06   4
PPM 095186     05:58:55.9 +29:59:01  7.5  0.23   5
PPM 095148     05:57:50.7 +29:48:46 10.0  0.15   5
98WS31         05:57:52.3 +29:57:54 15.8         5
Positions are for J2000

Event circumstances last updated at 2021/10/12 02:00:46 UT

Marc W. Buie, Southwest Research Institute

RECON